Making such medical needles by welding two portions, a first portion comprising a pointed end and the second portion being of tubular shape has been known for a long time, like for example from U.S. Pat. No. 1,613,206, granted on 4 Jan. 1927.
However, the medical needles that are currently most widely used do not have a structure obtained by joining two initially separate parts. Indeed, current requirements concerning the manufacturing quality of such needles are difficult to attain with conventional welding methods. Methods for spot welding two parts of cylindrical shape are known.
However, such “macroscopic type” methods are difficult to apply to parts as small as portions of medical needles whose diameters are currently of the order of several millimeters, or even less. Indeed, the application of a spot welding method would lead to the formation of small flashes all around the joint between the two portions of needle. The presence of these flashes is of course detrimental for the organic tissue on which the suture is carried out with a needle obtained by such a welding method.
Thus, current medical needles are typically made from a single metal portion one end of which is pointed whereas the second end is substantially planar. A blind hole is thus arranged in the second end for subsequently assuring the fixing of a suture thread. Generally, the blind hole is made by a laser or drill piercing method depending upon the dimensions desired.
This type of manufacturing method has, however, a significant drawback, because the very precise tolerances must be respected as regards the dimensions of the blind hole thereby obtained, in order to guarantee that the suture thread is properly held on the needle.
Another drawback of this type of manufacturing method is linked to the fact that if the blind hole is badly positioned or sized, it can happen that its walls are too thin to withstand the mechanical stresses subsequently experienced when a suture is performed.